1. Technical Field
The present invention relates generally to a semiconductor memory device and, more particularly, to a semiconductor memory device having internal circuits responsive to temperature data.
2. Discussion of the Related Art
A variety of semiconductor devices implemented by integrated circuit chips, such as CPUs, memories, gate arrays or the like, may be incorporated in a variety of electrical products, for example, but not limited to, portable personal computers, personal digital assistants (PDAs), servers, workstations or the like. If such electrical products are maintained in a sleep mode to save power, most of circuit components in the electrical product may remain in a turned-off state. Further, some semiconductor devices may continue to use power even in the sleep mode. For example, a volatile semiconductor memory device, such as, but not limited to, a dynamic random access memory (DRAM) may refresh data through memory cells so that the data stored in the memory cells may continue to be reserved, and thus consume power. In other words, the DRAM may consume the self-refresh power due to the required self-refreshing operation. Accordingly, it may be desirable to reduce power consumption in a battery-operated system that requires reduced power.
One attempt to reduce power consumption required for the self-refresh may be to change a refresh period depending on temperature. That is, as the power consumption at a lower temperature may be reduced by lowering a refresh clock frequency as compared to a higher temperature, the time period for which data may be reserved in the DRAM may become generally longer as temperature is reduced.
In the conventional art, an example of controlling power consumption by reducing power consumption upon the refresh operation may be that the refresh operation may be performed at a lower voltage when temperature is less than a desired value, while alternatively the refresh operation may be performed at a higher voltage when the temperature is more than the desired value.
Accordingly, the semiconductor memory device may include a refresh circuit as well as a variety of internal circuits therein.